This invention relates to a method and apparatus for laminating strips of thin or light gauge material to a backing material or substrate, and more particularly to laminating spaced narrow foil strips to a paper web.
In the packaging art, there are many containers for products which use liners consisting of a foil and paper laminant which are used to wrap the contents of a container. Excellent examples of this type of product container are the cigarette package and the candy wrapper. The cigarette package is primarily a paper foil liner surrounded by a label.
Processes for laminating foil to the paper are well known in the art. The liner used for cigarette packages is manually made by providing a foil web approximately 0.00025" in thickness and a paper web to which an adhesive is applied. The foil and paper are laminated together to form a composite web which is then slit into the proper width for use in the cigarette packages.
The foil used in the composite liner material was originally used in a moisture barrier; however, it has been found that the loss of moisture is not a significant problem in cigarette packages and, therefore, the foil laminant is not needed. The consuming public has, however, come to accept the foil barrier as being necessary and eliminating the foil from the cigarette liner would be quite detrimental when marketing the product.
For this reason, efforts have been made to laminate narrow foil strips on a wide paper web and use this strip laminated composite sheet for the cigarette package liner. There are two advantages to strip laminating. First, cigarette packages retain their present appearance with foil exposed on the ends of the package; and, secondly, there is a reduction in the amount of foil required, thereby reducing the cost of the packaging material and conserving our resources.
The use of stripped packaging material is not new in the cigarette packaging art; in fact, in 1891, T. J. Maloney obtained U.S. Pat. No. 452,109 on this concept. Prior to the present invention, there has been one way to laminate narrow strips of foil on a wide paper web. In this operation, a plurality of spaced rolls of a narrow foil stripping is unwound and nipped to a wide paper web having a striped adhesive pattern.
The strip lining material illustrated in U.S. Pat. No. 452,109 has not been used widely in cigarette packaging mainly because the greater expense and lesser efficiency of the previously known strip laminating method cannot be justified. Today, however, with conservation of resources becoming more and more important, strip laminating materials have become more and more attractive as packaging materials. Nevertheless, the presently known strip laminating techniques described above produce a multitude of problems and expenses. For example, the slitting operation for the foil to produce the narrow width rolls of light gauge foil is quite expensive. The handling of the increased number of small rolls of foil increases the possibility of damage to the foil which of course affects the scrap rate. But, the most critical problem concerns the delicate nature of the narrow thin gauge foil and maintaining the proper tension on all of the narrow webs. Foil webs, like webs of most other material, vary in thickness in the longitudinal machine direction as well as the transverse direction. This variance in thickness of the web makes it difficult to maintain the proper tension in the web so that you might get taunt webs next to slack webs.
Another problem is maintaining parallelism of all of the foil rolls. If parallelism is not maintained, tension on one edge of the foil can become greater than on the other edge. If all of the tension forces are directed to one edge of the foil, the edge will tear and the tear will progress across the web, causing a web breakage and machine downtime.
My strip laminating method overcomes most of the problems inherent in the multi-roll approach used and reduces others to a level where they become manageable.